Structure of human erythrocyte NADH-cytochrome b5 reductase

Acta Crystallogr D Biol Crystallogr. 2004 Nov;60(Pt 11):1929-34. doi: 10.1107/S0907444904020645. Epub 2004 Oct 20.


Erythrocyte NADH-cytochrome b(5) reductase reduces methaemoglobin to functional haemoglobin. In order to examine the function of the enzyme, the structure of NADH-cytochrome b(5) reductase from human erythrocytes has been determined and refined by X-ray crystallography. At 1.75 A resolution, the root-mean-square deviations (r.m.s.d.) from standard bond lengths and angles are 0.006 A and 1.03 degrees , respectively. The molecular structure was compared with those of rat NADH-cytochrome b(5) reductase and corn nitrate reductase. The human reductase resembles the rat reductase in overall structure as well as in many side chains. Nevertheless, there is a large main-chain shift from the human reductase to the rat reductase or the corn reductase caused by a single-residue replacement from proline to threonine. A model of the complex between cytochrome b(5) and the human reductase has been built and compared with that of the haem-containing domain of the nitrate reductase molecule. The interaction between cytochrome b(5) and the human reductase differs from that of the nitrate reductase because of differences in the amino-acid sequences. The structures around 15 mutation sites of the human reductase have been examined for the influence of residue substitutions using the program ROTAMER. Five mutations in the FAD-binding domain seem to be related to cytochrome b(5).

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Crystallography, X-Ray
  • Cytochrome-B(5) Reductase / chemistry*
  • Cytochrome-B(5) Reductase / genetics
  • Erythrocytes / enzymology*
  • Humans
  • Models, Molecular
  • Molecular Sequence Data
  • Mutation / genetics
  • Nitrate Reductases / chemistry
  • Protein Structure, Tertiary
  • Rats
  • Sequence Alignment
  • Zea mays / enzymology


  • Cytochrome-B(5) Reductase
  • Nitrate Reductases